Motor control system



July 31, 1934.

E. W. SEEGER ET AL MOTOR CONTROL SYSTEM Filed Oct. 4, 1930 Patented July3 l v v i UNiTEo STATES PATENT OFFICE MOTOR CONTROL SYSTEM Edwin W.Seeger, Wauwatosa, and John L. Deiandorf, Shorewood, Wis., asslgnors toCutler-Hammer, Inc., Milwaukee, Wis a corl ration of DelawareApplication October 4, 1930, Serial No. 486,352

2 Claims. (01. 172-239) This invention relates to improvements inmocited field windings f and F, respectively, which tor control systemsof the variable voltage type are supplied by an exciter E coupled to thedrive wherein the controlled motor has its armature of generator G Thefield winding f or motor connected with the armature of its supplygen- Mis shown as connected directly across the ex- I erator in a closed loop.v citer circuit,.whereas the field winding F of the 60 In such a systemit has been customary to generator G is connected to the'exciter throughprovide the generator with a series field in order a controller Cprovided on'the elevator car 1. to obtain under difierent loadconditions the The controller C, as will appear, provides for same speedfor a given setting of the control reversing the connections between thegenerator lo-element which is commonly a rheostat controlfield windingand the exciter and for including ling the shunt field of the generator.However, more or less resistance in series with the generthis provisionhas the disadvantage that when ator field winding. As will beunderstood, rethe motor is at a standstill and the generator versal ofthe field of the generator efiects reversal shunt field is opencircuited the series field tends of motor M while variation of theresistance in 35 to cause building up or the current in the armathecircuit of the generator field winding varies '79 ture loop resultingfrom the residual magnetism the potential impressed upon motor M. of thegenerator field. Also providing the main To this conventional systemthere is added a generator with a series field winding in additiongenerator (3* having a series field winding 1 said to the shunt fieldwinding has the disadvantage generator being connected in the loopincluding :0 that due to high induction of the shunt field the armaturesof motor M and generator G 75. winding variations in generator flux inresponse This auxiliary generator G is shown as coupled to changes inthe armature current are sluggish. to the main generator G to be driventherewith As an alternative to the provision of a series and its fieldwinding f is provided with a shortfield winding for the generator it hasheretofore circuit controllable by an electroresponsive switch beenproposed to provide the generator with an 2 which in turn is controlledby contacts 3 of the 130 additional field winding supplied with currentcar controller C. The arrangement is such that from a second generatorcoupled to the main when the car controller is in any runningposigenerator and excited by the current traversing tion it deenergizesthe switch 2 to open the short the armature loop, but this scheme alsohas the circuit around the field winding of auxiliary genaforementioneddisadvantage of sluggishness. erator G whereas when the elevatorcontroller The present invention has among its objects is thrown to oilposition its contacts 3 engageto' to provide a system overcoming theatoremenenergize switch 2 to short-circuitthe field windtioneddisadvantages of the systems heretofore ing 1". employed. The auxiliarygenerator G is preferably so de- 35 According to the present inventionit is prosigned that at full excitation it generates apposed to use inconjunction with a separately .exproximately ten percent of the maximumvoltage cited main generator a series wound auxiliary generated by themain generator. It is provided generator connected in the armature loopwith to act cumulatively with the main generator to provision forshort-circuiting the field o! the auxassist the latter under positiveload conditions 49 iliary generator when the motor is at a standand togenera a v a pp 150 that Of still. main generator to lower the totalvoltage supplied An embodiment oi the invention is diagramto thearmature of motor M when said motor is matically illustrated in theaccompanying drawoverhauled by its load. On the other hand, the ing andthe same will now be described, it being switch 2 provides forshort-circuiting the field f 45 understood that such embodiment iscapable of of the auxiliary generator when the controller C 109 variousmodifications without departing from the is thrown to oil position, thuseliminating the inscope of the appended claims. fiuenceoi' the auxiliarygenerator and permitting Referring to the accompanying drawing, the astrong dynamic braking action to bring the same shows a conventionalvariable voltage drive motor M to rest. Thus it will b pp t that a 80for an elevator car i, this drive comprising a mosystem wherein anauxiliary generator is so utitor M supplied from a generator Gr drivenby a lized will afiord the desired control of the motor constantlyrunning induction motor I. The mofree from the aforementioneddisadvantages of tor M has its armature connected ina closed the priorsystems. loop with the armature of the generator G and Considering thecontrol circuits, the same are 56 said motor and generator haveseparately exas follows- With the controller C in the position 110illustrated circuit may be traced from one side of the exciter byconductor 4 to the controller arm 5 and contact 6, by conductor 10through the field winding of generator G by conductor 11 to controllercontact 7, by arm 5 to and through resistance r, by conductors 12, 13and 14 to the 0pposite side 0! the, exciter. On the other hand, assumingmovement 01' the controller to the opposite side of its central positioncircuit may be traced as atoredesoribed to the controller arm 5 tocontact 8 and thence to cross connected contact 7 by conductor 11through the generator 'fleld' winding F by conductor 10 to controllercontact 6 and cross connected contact 9 through the controller arm andresistance r to the exciter, as

previously traced. As will be apparent, these circults provide forreversal oi the field of the main generator.

With the controller arm 5 in oil! or neutral position circuit may betraced from the exciter through said arm to contact 3 by conductor 15 toand through the winding 01' switch 2 by conductor 16 to conductor 14 andthence back to the exciten,

As previously stated, the field winding I oi. the

motor M is connected directly across the excitercircuit, it beingconnected by conductors l8 and 4 to one side of the exciter, andbyconductors 17 1 and 14 to the opposite side or said exciter.

1,sea,sss

What we claim as new and desire to secure by Letters Patent is:

1. In combination, a motor, a supply generator therefor, a closed loopincluding the armatures of said motor and generator, means controllingthe excitation 01 said generator to elect starting and stopping of saidmotor, a series wound auxiliary generator connected in said closed loop,and means under the control 01 the aforementioned control means toshort-circuit the field winding pendent i'or excitation upon the currenttraverslng said loop, means aflording a separate current supply uponwhich excitation of said main generator is wholly dependent, and meansto control excitation of said main generator' and to short-circuit thefield winding of said auxiliary generator when discontinuing-excitationof said main generator.

EDWIN W. BEEGER. JOHN L. DEI'ANDORF.

